[PATCH] wake up from a serial port

[PATCH] wake up from a serial port

[Guennadi Liakhovetski]

Enable wakeup from serial ports, make it run-time configurable over sysfs, 
e.g.,

echo enabled > /sys/devices/platform/serial8250.0/tty/ttyS0/power/wakeup

Requires

# CONFIG_SYSFS_DEPRECATED is not set

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>

---

Following suggestions from Alan and Russell moved the may_wake_up checks 
to serial_core.c. This time actually tested - it does even work. Could 
someone, please, verify, that put_device after device_find_child is 
correct? Also would be nice to test with a Natsemi UART, that can wake up 
the system, if such systems exist.

Thanks
Guennadi

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 9c57486..8a3d6ea 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1934,9 +1934,24 @@ static void uart_change_pm(struct uart_state *state, int pm_state)
 	}
 }
 
+struct uart_match {
+	struct uart_port *port;
+	struct uart_driver *driver;
+};
+
+static int serial_match_port(struct device *dev, void *data)
+{
+	struct uart_match *match = data;
+	dev_t devt = MKDEV(match->driver->major, match->driver->minor) + match->port->line;
+
+	return dev->devt == devt; /* Actually, only one tty per port */
+}
+
 int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
 {
 	struct uart_state *state = drv->state + port->line;
+	struct device *tty_dev;
+	struct uart_match match = {port, drv};
 
 	mutex_lock(&state->mutex);
 
@@ -1947,6 +1962,15 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
 	}
 #endif
 
+	tty_dev = device_find_child(port->dev, &match, serial_match_port);
+	if (device_may_wakeup(tty_dev)) {
+		enable_irq_wake(port->irq);
+		put_device(tty_dev);
+		mutex_unlock(&state->mutex);
+		return 0;
+	}
+	port->suspended = 1;
+
 	if (state->info && state->info->flags & UIF_INITIALIZED) {
 		const struct uart_ops *ops = port->ops;
 
@@ -1995,6 +2019,13 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
 	}
 #endif
 
+	if (!port->suspended) {
+		disable_irq_wake(port->irq);
+		mutex_unlock(&state->mutex);
+		return 0;
+	}
+	port->suspended = 0;
+
 	uart_change_pm(state, 0);
 
 	/*
@@ -2266,6 +2297,7 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
 {
 	struct uart_state *state;
 	int ret = 0;
+	struct device *tty_dev;
 
 	BUG_ON(in_interrupt());
 
@@ -2301,7 +2333,13 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
 	 * Register the port whether it's detected or not.  This allows
 	 * setserial to be used to alter this ports parameters.
 	 */
-	tty_register_device(drv->tty_driver, port->line, port->dev);
+	tty_dev = tty_register_device(drv->tty_driver, port->line, port->dev);
+	if (likely(!IS_ERR(tty_dev))) {
+		device_can_wakeup(tty_dev) = 1;
+		device_set_wakeup_enable(tty_dev, 0);
+	} else
+		printk(KERN_ERR "Cannot register tty device on line %d\n",
+		       port->line);
 
 	/*
 	 * If this driver supports console, and it hasn't been
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 773d8d8..60dedc0 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -291,7 +291,8 @@ struct uart_port {
 	unsigned long		mapbase;		/* for ioremap */
 	struct device		*dev;			/* parent device */
 	unsigned char		hub6;			/* this should be in the 8250 driver */
-	unsigned char		unused[3];
+	unsigned char		suspended;
+	unsigned char		unused[2];
 	void			*private_data;		/* generic platform data pointer */
 };
 

Re: wake up from a serial port

[Michael Mauch]

Guennadi Liakhovetski wrote:

> Enable wakeup from serial ports, make it run-time configurable over sysfs, 
> e.g.,
> 
> echo enabled > /sys/devices/platform/serial8250.0/tty/ttyS0/power/wakeup

Interesting, but how does that work from a user's/hardware perspective?

Do I have to pull DSR/RI to +12V? Can I use one of the other pins to get
these +12V (i.e. a switch and a resistor to shorten these pins is
enough)?

And probably in the BIOS I have to enable "wake on modem ring" (or
something similar)?

Regards...
		Michael

Re: wake up from a serial port

[Guennadi Liakhovetski]

On Wed, 12 Sep 2007, Michael Mauch wrote:

> Guennadi Liakhovetski wrote:
> 
> > Enable wakeup from serial ports, make it run-time configurable over sysfs, 
> > e.g.,
> > 
> > echo enabled > /sys/devices/platform/serial8250.0/tty/ttyS0/power/wakeup
> 
> Interesting, but how does that work from a user's/hardware perspective?
> 
> Do I have to pull DSR/RI to +12V? Can I use one of the other pins to get
> these +12V (i.e. a switch and a resistor to shorten these pins is
> enough)?
> 
> And probably in the BIOS I have to enable "wake on modem ring" (or
> something similar)?

It depends on the hardware. In principle, with this patch _if_ your system 
can suspend while keeping the UART powered on and the interrupt from this 
UART can wake up your system, then using this patch and the command above 
you'll be able to also keep the UART configured, i.e., prevent the driver 
from suspending it during suspend and then an interrupt from this UART 
will wake up the system. How you generate this interrupt - doesn't matter. 
Whether it is a received byte, or a modem line toggle, as long as it 
produces an interrupt, the system will wake up.

Don't know whether "normal" PCs can do that and if yes - how.

Thanks
Guennadi
---
Guennadi Liakhovetski

Re: [PATCH] wake up from a serial port

[Andrew Morton]

On Wed, 12 Sep 2007 20:50:10 +0200 (CEST)
Guennadi Liakhovetski <g.liakhovetski@gmx.de> wrote:

> Enable wakeup from serial ports, make it run-time configurable over sysfs, 
> e.g.,
> 
> echo enabled > /sys/devices/platform/serial8250.0/tty/ttyS0/power/wakeup
> 
> Requires
> 
> # CONFIG_SYSFS_DEPRECATED is not set
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> 
> ---
> 
> Following suggestions from Alan and Russell moved the may_wake_up checks 
> to serial_core.c. This time actually tested - it does even work. Could 
> someone, please, verify, that put_device after device_find_child is 
> correct?

Seems right to me, from reading device_find_child() and its associated
documentation.

> Also would be nice to test with a Natsemi UART, that can wake up 
> the system, if such systems exist.
>

It would help if you could provide simple-to-follow steps which a tester
should follow to perform this testing.

 > 
> diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
> index 9c57486..8a3d6ea 100644
> --- a/drivers/serial/serial_core.c
> +++ b/drivers/serial/serial_core.c
> @@ -1934,9 +1934,24 @@ static void uart_change_pm(struct uart_state *state, int pm_state)
>  	}
>  }
>  
> +struct uart_match {
> +	struct uart_port *port;
> +	struct uart_driver *driver;
> +};
> +
> +static int serial_match_port(struct device *dev, void *data)
> +{
> +	struct uart_match *match = data;
> +	dev_t devt = MKDEV(match->driver->major, match->driver->minor) + match->port->line;
> +
> +	return dev->devt == devt; /* Actually, only one tty per port */
> +}
> +
>  int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
>  {
>  	struct uart_state *state = drv->state + port->line;
> +	struct device *tty_dev;
> +	struct uart_match match = {port, drv};
>  
>  	mutex_lock(&state->mutex);
>  
> @@ -1947,6 +1962,15 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
>  	}
>  #endif
>  
> +	tty_dev = device_find_child(port->dev, &match, serial_match_port);
> +	if (device_may_wakeup(tty_dev)) {
> +		enable_irq_wake(port->irq);
> +		put_device(tty_dev);
> +		mutex_unlock(&state->mutex);
> +		return 0;
> +	}
> +	port->suspended = 1;
> +
>  	if (state->info && state->info->flags & UIF_INITIALIZED) {
>  		const struct uart_ops *ops = port->ops;
>  
> @@ -1995,6 +2019,13 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
>  	}
>  #endif
>  
> +	if (!port->suspended) {
> +		disable_irq_wake(port->irq);
> +		mutex_unlock(&state->mutex);
> +		return 0;
> +	}
> +	port->suspended = 0;
> +
>  	uart_change_pm(state, 0);
>  
>  	/*
> @@ -2266,6 +2297,7 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
>  {
>  	struct uart_state *state;
>  	int ret = 0;
> +	struct device *tty_dev;
>  
>  	BUG_ON(in_interrupt());
>  
> @@ -2301,7 +2333,13 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
>  	 * Register the port whether it's detected or not.  This allows
>  	 * setserial to be used to alter this ports parameters.
>  	 */
> -	tty_register_device(drv->tty_driver, port->line, port->dev);
> +	tty_dev = tty_register_device(drv->tty_driver, port->line, port->dev);
> +	if (likely(!IS_ERR(tty_dev))) {
> +		device_can_wakeup(tty_dev) = 1;
> +		device_set_wakeup_enable(tty_dev, 0);
> +	} else
> +		printk(KERN_ERR "Cannot register tty device on line %d\n",
> +		       port->line);
>  
>  	/*
>  	 * If this driver supports console, and it hasn't been
> diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> index 773d8d8..60dedc0 100644
> --- a/include/linux/serial_core.h
> +++ b/include/linux/serial_core.h
> @@ -291,7 +291,8 @@ struct uart_port {
>  	unsigned long		mapbase;		/* for ioremap */
>  	struct device		*dev;			/* parent device */
>  	unsigned char		hub6;			/* this should be in the 8250 driver */
> -	unsigned char		unused[3];
> +	unsigned char		suspended;
> +	unsigned char		unused[2];
>  	void			*private_data;		/* generic platform data pointer */
>  };
>  

Re: [PATCH] wake up from a serial port

[Greg KH]

On Wed, Sep 12, 2007 at 03:36:10PM -0700, Andrew Morton wrote:
> On Wed, 12 Sep 2007 20:50:10 +0200 (CEST)
> Guennadi Liakhovetski <g.liakhovetski@gmx.de> wrote:
> 
> > Enable wakeup from serial ports, make it run-time configurable over sysfs, 
> > e.g.,
> > 
> > echo enabled > /sys/devices/platform/serial8250.0/tty/ttyS0/power/wakeup
> > 
> > Requires
> > 
> > # CONFIG_SYSFS_DEPRECATED is not set
> > 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > 
> > ---
> > 
> > Following suggestions from Alan and Russell moved the may_wake_up checks 
> > to serial_core.c. This time actually tested - it does even work. Could 
> > someone, please, verify, that put_device after device_find_child is 
> > correct?
> 
> Seems right to me, from reading device_find_child() and its associated
> documentation.

Yes, that is correct.

thanks,

greg k-h

Natsemi UART owner test request (was Re: [PATCH] wake up from a serial port)

[Guennadi Liakhovetski]

On Wed, 12 Sep 2007, Andrew Morton wrote:

> On Wed, 12 Sep 2007 20:50:10 +0200 (CEST)
> Guennadi Liakhovetski <g.liakhovetski@gmx.de> wrote:
> 
> > Enable wakeup from serial ports, make it run-time configurable over sysfs, 
> > e.g.,
> > 
> > echo enabled > /sys/devices/platform/serial8250.0/tty/ttyS0/power/wakeup
> > 
> > Requires
> > 
> > # CONFIG_SYSFS_DEPRECATED is not set
> > 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > 
> > ---

[snip]

> > Also would be nice to test with a Natsemi UART, that can wake up 
> > the system, if such systems exist.
> 
> It would help if you could provide simple-to-follow steps which a tester
> should follow to perform this testing.

Ok, for anyone owning a system with a Natsemi UART and capable to suspend 
and resume it (you do not have to be able to resume it from the UART), 
would be great to have the patch below tested. For this you just have to 
apply the patch below, issue the above "echo" command to one of your 
Natsemi port, suspend and resume your system, and verify that your Natsemi 
port still works. If you are actually capable of waking up the system from 
that port, would be nice to test that as well.

Thanks
Guennadi

> > diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
> > index 9c57486..8a3d6ea 100644
> > --- a/drivers/serial/serial_core.c
> > +++ b/drivers/serial/serial_core.c
> > @@ -1934,9 +1934,24 @@ static void uart_change_pm(struct uart_state *state, int pm_state)
> >  	}
> >  }
> >  
> > +struct uart_match {
> > +	struct uart_port *port;
> > +	struct uart_driver *driver;
> > +};
> > +
> > +static int serial_match_port(struct device *dev, void *data)
> > +{
> > +	struct uart_match *match = data;
> > +	dev_t devt = MKDEV(match->driver->major, match->driver->minor) + match->port->line;
> > +
> > +	return dev->devt == devt; /* Actually, only one tty per port */
> > +}
> > +
> >  int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
> >  {
> >  	struct uart_state *state = drv->state + port->line;
> > +	struct device *tty_dev;
> > +	struct uart_match match = {port, drv};
> >  
> >  	mutex_lock(&state->mutex);
> >  
> > @@ -1947,6 +1962,15 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
> >  	}
> >  #endif
> >  
> > +	tty_dev = device_find_child(port->dev, &match, serial_match_port);
> > +	if (device_may_wakeup(tty_dev)) {
> > +		enable_irq_wake(port->irq);
> > +		put_device(tty_dev);
> > +		mutex_unlock(&state->mutex);
> > +		return 0;
> > +	}
> > +	port->suspended = 1;
> > +
> >  	if (state->info && state->info->flags & UIF_INITIALIZED) {
> >  		const struct uart_ops *ops = port->ops;
> >  
> > @@ -1995,6 +2019,13 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
> >  	}
> >  #endif
> >  
> > +	if (!port->suspended) {
> > +		disable_irq_wake(port->irq);
> > +		mutex_unlock(&state->mutex);
> > +		return 0;
> > +	}
> > +	port->suspended = 0;
> > +
> >  	uart_change_pm(state, 0);
> >  
> >  	/*
> > @@ -2266,6 +2297,7 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
> >  {
> >  	struct uart_state *state;
> >  	int ret = 0;
> > +	struct device *tty_dev;
> >  
> >  	BUG_ON(in_interrupt());
> >  
> > @@ -2301,7 +2333,13 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
> >  	 * Register the port whether it's detected or not.  This allows
> >  	 * setserial to be used to alter this ports parameters.
> >  	 */
> > -	tty_register_device(drv->tty_driver, port->line, port->dev);
> > +	tty_dev = tty_register_device(drv->tty_driver, port->line, port->dev);
> > +	if (likely(!IS_ERR(tty_dev))) {
> > +		device_can_wakeup(tty_dev) = 1;
> > +		device_set_wakeup_enable(tty_dev, 0);
> > +	} else
> > +		printk(KERN_ERR "Cannot register tty device on line %d\n",
> > +		       port->line);
> >  
> >  	/*
> >  	 * If this driver supports console, and it hasn't been
> > diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> > index 773d8d8..60dedc0 100644
> > --- a/include/linux/serial_core.h
> > +++ b/include/linux/serial_core.h
> > @@ -291,7 +291,8 @@ struct uart_port {
> >  	unsigned long		mapbase;		/* for ioremap */
> >  	struct device		*dev;			/* parent device */
> >  	unsigned char		hub6;			/* this should be in the 8250 driver */
> > -	unsigned char		unused[3];
> > +	unsigned char		suspended;
> > +	unsigned char		unused[2];
> >  	void			*private_data;		/* generic platform data pointer */
> >  };
> >  
> 

---
Guennadi Liakhovetski